Banding machine for logs of sheet material

ABSTRACT

Banding machine for logs ( 1 ) of sheet material fed by a conveyor belt ( 2 ) to a packaging apparatus adapted to band it with a banding web ( 11 ) up to form a tubular wrapper around it. The packaging apparatus of the banding machine comprises a pusher ( 7 ) operated by an actuator ( 8 ), which pushes the log ( 1 ) in a channel ( 10 ) where a packaging sheet ( 11 ) is arranged stretched in front of the log, as an obstacle, along all the length of the machine through a passage ( 12 ). According to the invention, the conveyor belt ( 2 ) and the packaging apparatus ( 7 ) are arranged at different heights, respectively at a first and a second height (H 1  and H 2 ). Another pusher ( 14 ) can be provided, operated by a cylinder piston ( 15 ) at a first height (H 1 ), in addition to the pusher ( 7 ) at the second height (H 2 ), independent from each other. Furthermore, a lifting member ( 13 ) is provided, which receives the log ( 1 ) from the first pusher ( 14 ) and moves from the first height (H 1 ) to the second height (H 2 ). At its inlet in the banding machine the log ( 1 ) can be not compressed and is compressed up to reaching a compact shape indicated as ( 1 ′) when passing from the first height (H 1 ) to the second height (H 2 ). In particular, the lifting member ( 13 ) while lifting the log compresses at the same time the log ( 1 ) against a fixed wall ( 16 ), up to causing the log to achieve a compact configuration ( 1 ′).

FIELD OF THE INVENTION

The present invention relates to the production of stacks of papermaterial, and, in particular, it relates to a banding machine for logsof folded, overlapped or interfolded sheet material, for arrangingaround a log a tubular wrapper of paper and the like.

BACKGROUND OF THE INVENTION

As well known, in the paper converting industry a variety of types isused of machines and of processes for making paper tissues, paper towelsand similar articles from stacks of folded, overlapped or interfoldedsheets of a certain height.

The stacks are obtained folding the sheets and simply overlapping themon one another or interfolding them, i.e. at each fold a wing of theprevious sheet and a wing of a next sheet of the stack engage with eachother. This way, when drawing a sheet from a package, at the moment ofthe use, also a wing of a next sheet of the stack is dragged up toprotruding from the package, with subsequent practical utilization forcertain types of users. Among possible interfolding ways the L-type,with 2 folds (single fold), or the Z or W types, respectively with 3 and4 folds (multi fold), are known.

After a step of separation of a pack from the stack, once achieved ameasured height of the pack, a step follows of conveying the packs orlogs for following treatment and packaging.

The stacks of folded or interfolded sheets from which a log is formedhave a length that depends on the width of the starting web, normallyabout 2 metres and more.

For example, in case of logs of interfolded products exiting from thehead of an interfolding machine, according to the type of interfoldedproduct and then to the final use, said log can be conveyed to atransversal cutting machine forming small packages of predeterminedlength and then forwarding them to a binder that puts them in wrapperstailored for the users. With this solution, normally, the so-called“facial tissue” products are packaged.

Alternatively, the products can be distributed as banded packs or clips,as is the case of “hand towels”, which can be put in special fixeddistributors with standard shape. In this case, the whole log ofinterfolded product, normally, is first compressed and then banded by aweb that covers it around, creating a tubular wrapper. The banded log isthen cut off into single small packages or clips that are already bandedby a corresponding cut tubular wrapper portion.

In the latter case, for carrying out the banding machine step, bandingmachines are used located downstream of the interfolding machine. Inparticular, the log of interfolded sheets produced and exiting from theinterfolding machine can be carried directly into the banding machine bymeans of an appropriate conveying system, such as a conveyor belt.

A diagrammatical view of the operation of a known banding machine isdescribed in FIGS. 1-4, respectively a longitudinal sectional view andcross sectional views of three successive operation steps with respectto the log. With reference to FIG. 1, a log 1 of interfolded or foldedmaterial is carried by a conveyor belt 2 in a banding machine of priorart. At its inlet into the banding machine log 1 meets a path setbetween two overlapping conveyor belts 3 and 4 that gradually decreasetheir relative distance in the vertical direction in order to compresslog 1 reaching eventually a compressed configuration 1′ between twooverlapped conveyor belts 5 and 6. Once compressed the logs are bandedby means of a wrapper 11 (FIGS. 2-4) cut from a web, by a pusher 7operated by an actuator 8 that pushes log 1 into a channel 10 of themachine in order to carry out the packaging. More precisely, log 1′compressed is pushed into channel 10, and a cut sheet of web 11 isarranged stretched in front of the log as an obstacle along all thelength of the machine through a passage 12. In a way not shown the cutsheet of web 11 is automatically unwound from a roll and cut at apredetermined length. By the action of a pusher 7, operated by acylinder piston 8, which pushes the log against the stretched sheet wellbeyond passage 12, a kind of self-packaging is carried out, i.e. the logis wound by the sheet for ¾ of its side surface. Then, after thewithdrawal of pusher 7, a system of plates 9 transversal to channel 10is actuated, which aligns to log 1′ the remaining wings of sheet 11, onone of which glue was previously spread, so that they are closed in turnon the free side of log 1′. Then, further compressed and banded logs arepushed progressively forward against log 1′, which moves in channel 10up to an outlet where it is withdrawn in a way not shown.

In other embodiments, instead, there is a movable upper support thatcompresses the log from the above on a conveyor belt once reached apredetermined position, thus reducing the volume and the height of thelog before packaging. For example, a machine of this type is describedin EP1636093.

During the forward and back strokes of the pusher, the conveyor beltmust stop for allowing the return stroke of the pusher. For example, incase of a one meter travel of the pusher, i.e. about half metre offorward stroke and half metre of back stroke, a certain time isnecessary, which causes a reduction of productivity, for allowing theback stroke of the pusher.

It is therefore desirable for improving productivity to minimize thewaiting time.

Concerning the step of compressing, a similar system is described inU.S. Pat. No. 6,865,861. In this case, two conveyor belts decrease theirrelative distance (see also FIG. 1), and there would be an improvementof productivity with respect to the case of a single conveyor belt andpusher. In fact, while in the first case the log is compresses duringits inlet in the machine, in the latter case the log must be completelyentered in the banding machine for pressing it, increasing the waitingtime.

In U.S. Pat. No. 6,865,861 there is then the need to feed the web thatis used for wrapping the log causing the web to be frictionally draggedby the log same. This has the drawback that the speed, and then theproductivity, must to be low, and the compression of the log cannot beexcessive, to avoid break of the banding machine web, or to avoiddifficulty of introduction and drag of the latter between the conveyorbelts and the log same.

SUMMARY OF THE INVENTION

It is therefore a feature of the present invention to provide astructure of banding machine that has a high productivity and at thesame time it is as compact as possible.

In particular, it is a feature of the present invention to provide astructure of banding machine that separates the path of the pusher fromthat of the conveyor belt of the log, thus increasing productivity.

These and other objects are achieved by a banding machine for logs offolded, overlapped or interfolded sheet material, comprising:

-   -   a conveyor belt adapted to carry a not compressed log in said        banding machine;    -   means for packaging the log, putting a web for banding the log        in a position adapted to receive said log and to band it        creating a tubular wrapper around it;    -   pushing means adapted to push said log from said conveyor belt        towards said means for packaging;    -   wherein said conveyor belt and said means for packaging are        arranged at different heights, respectively at a first and a        second height;    -   wherein said pushing means have at least a first pusher at said        first height and at least a second pusher at said second height        independent from each other;    -   and wherein lifting means are provided adapted to bring a log        from said first to said second height, at said first height said        first pusher pushing the log from said conveyor belt to said        lifting means, and at said second height said second pusher        pushing said log from said lifting means against said web in        said means for packaging.

Preferably, when passing from said first height to said second heightsaid lifting means compresses at the same time said log.

Advantageously, said lifting means push said log against a fixed walllocated at said second height, for compressing said log before theintervention of said second pusher.

In an exemplary embodiment, two different means for packaging areprovided which are located respectively at said second height and at athird height, wherein said third height is, in particular, less thansaid first height, said lifting means comprising two lifting platformsadapted to operate independently from each other, initially locatedrespectively at the first and at the third height.

This way, while the first plate at the first height receives a log fromthe conveyor belt and pushes it against the fixed wall located at thesecond height, the second plate moves at the same time from the thirdheight to the first height for receiving a next log. Furthermore, withreference again to the movement from said first height to said thirdheight, the second plate can work as fixed wall for the log by movingback the second plate from the second height to the first height.

According to another aspect of the invention, a method for banding a logof folded, overlapped or interfolded sheet material comprises at leastone of above defined steps.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristic and the advantages of the banding machine,according to the invention, will be made clearer with the followingdescription of an exemplary embodiment thereof, exemplifying but notlimitative, with reference to the attached drawings, in which likereference characters designate the same or similar parts, throughout thefigures of which:

FIGS. 5 and 6 show diagrammatically in a longitudinal cross sectionalview two successive steps of operation of a banding machine according tothe invention;

Figures from 7 to 11 show diagrammatically a cross sectional view withrespect to the log of five operative successive steps of the bandingmachine of FIGS. 5 and 6 according to the invention;

Figures from 12 to 17 show diagrammatically a cross sectional view withrespect to the log of six operative successive steps of an exemplaryembodiment of the banding machine according to the invention.

DESCRIPTION OF A PREFERRED EXEMPLARY EMBODIMENT

As shown in FIGS. 5-11, relatively to a first exemplary embodiment ofthe invention, a log of interfolded material 1, just produced by aninterfolding machine, comes on a conveyor belt 2 in the banding machine,for example a machine of prior art, or an improved banding machine asthat described in an european patent application filed on the same dayin the name of the same applicant.

At its inlet in the banding machine log 1 is not compressed and has tobe compressed up to reaching a compact shape indicated as 1′, for beingthen fed to a packaging apparatus adapted to band it with a banding web11 up to form a tubular wrapper around it, in a way similar to thatindicated in figures from 2 to 4. The packaging apparatus comprises apusher 7 operated by an actuator 8, which pushes log 1 in a channel 10where a packaging sheet 11 is arranged stretched in front of the log, asan obstacle, along all the length of the machine through a passage 12.

According to the invention, conveyor belt 2 and the packaging apparatusare arranged at different heights, respectively at a first and a secondheight H1 and H2.

A first pusher 14 is provided, operated by a cylinder piston 15 at firstheight H1, in addition to pusher 7 at second height H2, independent fromeach other. Furthermore, a lifting member 13 is provided, which receiveslog 1 from the first pusher 14 and moves from first height H1 to secondheight H2.

In more detail, as shown in FIGS. 5, 7 and 8, lifting member 13 receiveslog 1 from conveyor belt 2. When passing from the first height to thesecond height (FIGS. 6 and 9) lifting member 13 compresses at the sametime log 1 against a fixed wall 16, up to reaching a compactconfiguration 1′.

Then, second pusher 7 starts moving (FIG. 10), causing packaging sheet11 to band the log, in a known way. In particular, pusher 7 pushes thecompacted log 1′ into channel 10 against packaging sheet 11, stretchedin front of log 1′ through passage 12, so that log 1′ is wound for ¾ bysheet 11. Then, after the withdrawal of pusher 7, a system of plates 9(shown only in FIG. 11) transversal to channel 10, pushes the remainingwings of sheet 11 adjacent to log 1′, on which glue was previouslyspread in a way not shown, causing them to adhere in turn on the freeside of log 1′. Logs 1″ compressed and previously banded (FIG. 10), arepushed progressively forward up to the outlet of channel 10.

The advantage of the invention consists of the fact that, while liftingmember 13 is being raised, creating compressed log 1′, a next log la canarrive on the web 2 (FIG. 9), and while pusher 7 is causing log 1′ to bebanded (FIG. 10), lifting member 13 can lower again for then receiving(FIG. 11) next log 1 a.

In an exemplary embodiment of the invention, shown in figures from 12 to17, two different means for packaging are provided which are locatedrespectively at second height H2, consisting of channel 10 and pusher 7,and at a third height H3, consisting of channel 20 and pusher 17, wherethe third height H3 is, in particular, lower than first height H1. Thelifting means comprises two lifting platforms 13, 23 adapted to operateindependently from each other, initially located respectively at thefirst and at the third height H1 and H3.

In more detail, as in the previous case, lifting member 13 receives log1 from conveyor belt 2 (FIGS. 12 and 13). When passing from first heightH1 to second height H2 (FIG. 14) lifting member 13 compresses log 1against fixed wall 16, up to reaching a compact configuration 1′.

Then, second pusher 7 starts moving (FIG. 15), causing packaging sheet11 to band the log, in a way similar to that described with reference toFIGS. 9 and 10.

In the meantime, while lifting member 13 is raising creating compressedlog 1′, a log 1 a is waiting on belt 2 (FIG. 14). Second lifting member23 is then brought to first height H1 for receiving it and when pusher 7has started to band log 1′, pusher 14 moves log 1 a onto second liftingmember 23 (FIG. 15). In the meantime, a log 1 b is waiting on web 2(FIG. 16). Second lifting member 23 is at the same time brought to thirdheight H3 along with log 1 a and, when pusher 7 has started to band log1′, first lifting member 13 can lower again to first height H1,compressing log 1 a that was present on the lifting member 23 at thethird height H3, creating a compressed log 1′a (FIG. 16). Finally, whilepusher 17 is causing log 1′a to be banded (FIG. 17), lifting member 13already, which has been lowered back to height H1, can receive next log1 b.

This solution is particularly compact and integrates two bandingapparatus, allowing to receive logs on the conveyor belt at higher rateand to deliver them immediately.

Notwithstanding in the description reference has been made to a step ofcompression of the log in the passage from the first at the secondheight, it is not excluded that the log can arrive already compressed onconveyor belt 2. Even in this case, the log is fed to the bandingmachine at different heights with respect to pusher 7 allowing a higherproductivity for the fact that conveyor belt 2 or other conveyor beltsmust not await the end of the stroke of pusher 7 in the two directionsin order to supply a log for banding.

The foregoing description of a specific embodiment will so fully revealthe invention according to the conceptual point of view, so that others,by applying current knowledge, will be able to modify and/or adapt forvarious applications such an embodiment without further research andwithout parting from the invention, and it is therefore to be understoodthat such adaptations and modifications will have to be considered asequivalent to the specific embodiment. The means and the materials torealise the different functions described herein could have a differentnature without, for this reason, departing from the field of theinvention. It is to be understood that the phraseology or terminologyemployed herein is for the purpose of description and not of limitation.

1. Banding machine for logs of sheet material, comprising: a conveyorbelt adapted to carry a log in said banding machine; means for packagingthe log, said means for packaging being adapted to put a web for bandingthe log in a position adapted to receive said log and to band itcreating a tubular wrapper around it; pushing means adapted to push saidlog from said conveyor belt towards said means for packaging;characterized in that said conveyor belt and said means for packagingare arranged at different heights, respectively at a first and a secondheight; Said pushing means have at least a first pusher at said firstheight and at least a second pusher at said second height independentfrom each other; lifting means are provided adapted to bring a log fromsaid first to said second height, at said first height said first pusherpushing the log from said conveyor belt to said lifting means, and atsaid second height said second pusher pushing said log from said liftingmeans against said web in said means for packaging.
 2. Banding machineaccording to claim 1, wherein when passing from said first height tosaid second height said lifting means compresses at the same time saidlog.
 3. Banding machine according to claim 1, wherein a fixed wall isprovided located at said second height against which said lifting meanspush said log for compressing it before the intervention of said secondpusher.
 4. Banding machine according to claim 1, wherein two differentmeans for packaging are provided which are located respectively at saidsecond height and at a third height.
 5. Banding machine according toclaim 4, wherein said third height is lower than said first height. 6.Banding machine according to claim 4, wherein said lifting meanscomprises two lifting platforms adapted to operate independently fromeach other, initially located respectively at the first and at the thirdheight.
 7. A method for banding a log of sheet material, comprising thesteps of: conveying a log in said banding machine; packaging the log, bybringing a banding web in a position adapted to receive said log and toband it creating a tubular wrapper around it; pushing said log from saidconveyor belt towards said banding web for causing said banding;characterized in that said step of conveying and said step of packagingoccur at different heights, respectively at a first and a second height;said step of pushing is carried out in part at said first height and inpart at said second height independently; a step is provided of passagefrom said first to said second height between said two pushing steps. 8.Method according to claim 7, wherein when passing from said first heightto said second height the compression of said log is provided.
 9. Methodaccording to claim 7, characterised in that said steps are executedaccording to claims from 3 to 6.